Aeronautical Wind Tunnel Specifications and Schematics

UC Davis Aeronautical Wind Tunnel (AWT) is used for both university affiliated research. The AWT is an open circuit tunnel with a 33.6″ x 48″ closed test section. A 125 horsepower motor produces a maximum velocity of 165 mph through the test section. Turbulence levels have been determined to be < 0.1% throughout the velocity range. A pyramidal balance measures all six force and moment components over a wide range of angle of attack and angle of yaw.

Contraction Section

Contraction Section

Contraction ratio: 7.5:1

An aluminum honeycomb 6″ deep with .25″ cells (aspect ratio of 24) is located in the welded steel entrance chamber, protected by a coarse screen at the inlet. The honeycomb is followed by four 20 x 20 mesh (.009″ dia.) stainless steel anti-turbulence screens. Space is left for one additional screen.

The section is composed of four sides of identical curvature to provide equal pressures on adjoining sides at the corners to guard against the formation of corner vortices.

The coordinates of the contraction is derived from a ninth-order polynomial with three derivatives equated to zero at the entrance and five at the exit providing extremely gradual transition from and to axial flow.

Test Section

Test section, looking in direction of flow

Dimensions: 33.6″ x 48″ x 12′

Two 36″ turntables in the floor.

The test section is constructed with parallel sides instead of the usual practice of diverging two sides to allow for boundary layer growth. Four tapered fillets are installed in the test section to compensate for the narrowing of the flow channel due to boundary layer growth and to provide a constant static pressure throughout the test section.

Aluminum floor and ceiling. Side walls are clear plexiglass panels hinged at the top to provide four 64″ wide doors centered on each of the two turntables. The doors can be removed and replaced with special glass doors as necessary.

An 18″ ultraviolet light (F18T8-BLB) installed in one of the lower fillet panels can illuminate the upstream turntable for fluorescent visualization applications.

Illumination is provided by two 96″ fluorescent tubes (F96T8-SSCW) installed in the upper fillet panels.

Balance, Measurement and Positioning Systems

Pyramidal balance system installed under the upstream turntable:
– Measures all six components of force and moment
– Positions model angle of yaw and angle of attack
– Calibrated as defined in the following document: calibration procedures

Pitot Static Calibration

Pyramidal Scale Calibration

Load and positioning limits:

Lift

±300 lb

Drag

±50 lb

Side Force

±150 lb

Pitching Moment

± 70 ft-lb

Rolling Moment

± 50 ft-lb

Yawing Moment

± 50 ft-lb

Angle of Attack

± 35 deg

Angle of Yaw

± 45 deg

Model positioning is performed by three Size 34 Slo-Syn stepper motors by the Superior Electric division of Warner Electric.

A two dimensional traversing mechanism installed from the ceiling of the test section is capable of moving a probe (e.g., hot wire, pitot tube) within a plane normal to the air flow. The traversing system can be manually placed at various longitudinal stations in the test section.